We don't know enough of Jill nor Josy to make a statement like this. the only character who we know more than enough is Maya. Jill and Josy is still a mystery, a many thing about Jill is trully just simps headcanons

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as for Jill helping Maya
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I think we do know enough. Josy's clearly not inexperienced with guys as evidenced by how well she handles the MC's dick and Maya asking her for advice about how to please a guy. She seems to have gotten together with Maya on a whim because she found out Maya had a thing for her and probably thought, "What the hell?", and went with it in that moment. From there, real feelings probably developed for Josy and so they became a couple in secret.
This wasn't likely Josy having some magical, sapphic seductive powers since we know from Maya that she never really connected with any guys before and from the mini-flashback in Ep 6, we see how she was let down by guys in the past. Josy, as her close friend, likely gave her the attention and affection she wanted from guys and so she developed a romantic crush on her and from that believed she must be lesbian since she'd never felt that way for a guy before.
Jill is a very reserved person, not just with regards to sex, but in general. She seems very much like an old romantic, believing in monogamy, and in following certain rules when it comes to dating and intimacy. Having sex with the MC is not necessarily going to change that, especially since it will be enough for her just to have had sex with a guy that the idea she's now also going to be into girls is quite a stretch, and as I've just said, Josy is not a sapphic seductress who will make Jill want that.
As for Jill helping Maya, why not? Jill and Josy becoming close friends could mean that Jill, in her kind and generous nature, may offer to help Maya financially or legally if she becomes aware of Maya's predicament, and she'd do this as a favour to Josy because they are friends.